Dual wave generator



c. K. GIERINGER DUAL WAVE GENERATOR March 9, 1943.

Filed 001;. 4, 1940 Patented Mar. 9, 1943 2,313,427 mun. wnvn cam-mama Carl K. 'Gleringcr, Cincinnati, Ohio, assignor to 'lhe Liebel-Flarsheim Company, Cincinnati,

Ohio, a corporation of Ohio Application October 4, 1940, Serial No. 359,756 ZClaims. (Cl. 128-422) This invention relates to electrotherapeutic machines of th type employed in treating body ailments. It is directed particularly to a machine embodying an oscillating circuit which is capable of providing short wave and ultra short wave oscillations selectively and to means ior'controlling the machine so that it oscillates within the range best suited to the type of treatment being given.

In the use of a diathermy machine the energy is applied to the patient by means of applicators or electrodes which are of diflerent types, de-. pending upon the kind of treatment to be given. Cable or drum electrodes, which are adapted to be placed around, or directly adjacent, an atflicted area, operate inductively upon the patient.

It has been determined that the best results are obtained with this type of equipment when the energy supplied is of short wave length, e. g., ten

to thirty meters; the wave length commonly employed in such instances is approximately twentythree meters. On the other hand, experience has indicated that the most satisfactory results are obtained with capacitively operated air spaced electrodes and certain other types, it they be upon energy of ultra short wave length; approximately five to ten meters. So-called pads and cuffs operate substantially equally well on short wave or ultra short wave oscillations.

The air spaced electrodes are adapted particularly for use about the head or in instances when contact of the electrodes with the body is impractical or undesirable. Inductance cables are wrapped around the part to be treated, or otherwise draped over it appropriately, and these provide electromagnetic inductance. Treatment drums which may be curved or fiat are of the same general type but the electrodes themselves are located in predetermined portions in the units in order that they may be applied conveniently to local regular or irregular parts of the body. Padsand cufls are provided to give the doctor greater latitude in his selection of electrodes for various treatment conditions.

For diathermy treatments it heretofore has been necessary that the doctor either have two machines, one a short wave generator for use in conjunction with inductance cables or drums, and the other an ultra short wave generator for use in conjunction with space plates and the like,

or, in the alternative, a single machine capable of being adjusted manually to provide energy at the respective wave lengths. Machines of the latter type have been available in the past, but

the doctor or operator manipulate it manually in order that the machine generate either short wave or ultra short wave energy.

It has been generally appreciated that short wave energy is best suited for use in conjunction with inductive electrodes and that ultra short wave energy is best suited for use in conjunction with electrodesof the capacitive type; The primary difficulty and inconvenience has come about by virtue of the fact that the operators, through mistake, neglect to manipulate the switches and frequently leave the machine set to provide ultra short wave oscillations when inductive electrodes are being used, or vice versa. As a result, the treatment conditions are ineflicient and the ma chines are not put to their best usage. Moreover, the necessity for switching manipulations coupled with the necessary care and attention in the tuning operations makes the set-up and adjustment of the machine somewhat complex and requires considerable part of the operators time.

The principal object of the present invention has been to simplify the operation and adjustment of a diathermy machine. In accordance with this objective the invention, generally speaking, contemplates two features. First, an oscillating circuit is provided in a diathermy machine which is capable potentially of operating both as a short wave generator and as an ultra short wave generator, or a dual wave device which can be controlled selectively and conveniently to operate at one wave length or at the other. Next, the invention contemplates a simple and automatic means for controlling the wave length at which the machine is caused to operate, and in this respect the improvement contemplates circuit switching means which is operable automatically in accordance with the type of electrode selectedby the doctor and connected to the machine. 0therwise expressed, the control of the machineis provided at the time of connection of an electrode to the machine. In the preferred embodiment the electrode itself physically operates appropriate switching means through which the wave length at which the device operates is automatically determined.

In some diathermy machines being used at the present time separate sets of receptacles are provided for the respective drum or cable (inductance) and space plate capacitive electrodes may be inserted. In the preferred machines of the present improvement the oscillator circuit is adjusted'normally to operate as an ultra short wave generator and no circuit switching or confor the use of them it has been necessary that trol is either requisite or exercised when space plate electrodes are inserted in the receptacles designated for these applicators.

Upon' the ins rtion or.connection of cables or drums, however, which operate best at the short wave length, a switch is operated which in turn exercises a control upon the generator circuit and causes it to operate as a short wave device. In this manner the improvement makes it impossible for the doctor, by mistake or otherwise, to operate the machine as a short wave device when capacitive type applicators are being uti1ized,,or as an ultra short wave device when inductive type applicators are to be employed. No physical manipulation of service is required and therefore no time is required for the set-up and adjustment of the machine.

For convenience the dual wave generator and the circuit switch means by which these improvement results have been obtained are described in the order named in the specification which follows.

In the preferred embodiment of the invention, an oscillator of the push-pull type is utilized. The plate circuit of this apparatus embodies a high inductance coil with which a condenser of relatively high capacitance is connected in parallel. These elements provide the means in the plate circuit through which the apparatus is rendered capable of operating at short wave length. The plate circuit also comprises low inductance tank coil means, and aside from the condenser, the distributed capacity of the plate circuit is sufficiently low to enable the oscillator potentially to operate also at ultra short wave length. In other words, two circuit paths are provided in the plate circuit; one potentially determines the operation of the device as a short wave generator, and the other as an ultra short wave generator.

The grid circuit in turn comprises a coil means of relatively large inductance and coil means of relatively small inductance. These grid coil means are adjusted to furnish the excitation whereby the high capacitance-high inductance of the plate circuit, on the one hand, or the low inductance-low capacitance of the plate circuit, on the other hand, respectively determine the wave length of the output energy. Thus, the high inductance-high capacitance means in the plate circuit cooperates with the high inductance means in the grid circuit, enabling the oscillator to furnish short wave energy, and vice versa, the low inductance-low capacitance: in the plate circuit cooperates with the low inductance means in the grid circuit to enable the oscillator to furnish ultra short wave energy.

Next, in the preferred arrangement the selection and control by which the oscillator is caused to provide energy of the one wave length or the other is exerted through the short-circuiting of inductance of the grid circuit. This operation renders ineffective the portion of the inductance which is shunted, and the oscillator is thereby converted to furnish energy at other wave length.

.The second feature of the improvement contemplates a switch physically operated upon the insertion of an inductive type: electrode in an appropriate receptacle therefor, for control of the grid coil shunt. In the preferred embodiment this switch is positioned adjacentthe receptacle of the electrode and is arranged to be closed when the electrode plug is inserted in .the receptacle. The shunting switch may be located in a shunt connection across a portion of the total grid coil or, better still, in a circuit including a high frequency relay through which another switch is operated for short circuiting the predetermined grid coil portion. The latter arrangement is preferred because'of the desirability of maintaining symmetry in the grid circuit which normally tends to be destroyed when leads from switches or other members remotely located are adjacent this portion of the apparatus'.

From the foregoing principles upon which the invention is based and the following detailed description of a preferred embodiment, those skilled in the art readily will comprehend the various other circuits in which the improvements may be utilized.

In the drawing:

Figure 1 is a diagrammatic view of a simplified oscillating circuit.

Figure 2 is a diagrammatic illustration of the apparatus for the operation of the circuit control switch.

The circuit which is shown in Figure 1 comprises a pair of electron tubes I and 2. Each tube is comprised of a plate element 3, a grid element 4 and a filament element 5.

As shown in Figure 1, the circuit includes a high inductance tank coil 8 and a high capacitance condenser 1 and also includes low inductance coils 8 and 8. Plate 3 of the tube l is connected through lead 10 to one terminal of the coil 8, and the other terminal of the coil is, in turn, connected to one end of the tank coil 6 through lead ll. Likewise, the plate 3 of the tube 2 is connected, through lead l2, to one end of coil 9 and the other end of this coil is connected to the other terminal of the tank coil 6 through the lead l3. The condenser 1 is connected across the leads II and I3 to shunt the tank coil 6. For convenience, the tank coil 6 is sometimes hereinafter referred to as the short wave tank coil and the coils 8 and 9 as the ultra short wave tank coils of the plate circuit.

The grid circuit includes inductances l4 and I5, and also an inductance iii of higher value than the inductances l4 and I5 and connected in series with them. The outer terminals of the inductances I4 and I5 are connected through the leads I1 and I8 to the grids 4 of the respective tubes 1 and 2. In the preferred circuit, all inductances are so arranged as to value that when the machine -is operating as a short wave generator, the wave length is determined essentially by the tank coil 6 and the condenser 1 in .the plate circuit, and so that the excitation for the grid circuit is derived principally through the coils l4, l5 and i6.

A grid leak resistor I9 is connected across the leads 2!] and 2|, the former being tapped to the grid coil [6 and the latter being connected to one of the leads 23, 24 interconnecting the filaments 5 of the tubes I and 2. A plate voltage supply 25 is connected to the lead 2| and a lead 28 which'is tapped to the tank coil 6 to supply the input power for the circuit.

Thus, it will be seen that the plate or tank circuit of the device includes short wave tank coil means 6 and the ultra short wave coil means 8 and 9, and the grid circuit is adjusted, e. g.

respectively are inductively coupled to the coils in the plate circuit of the generator. Lead 30 terminates in a plug receptacle which is adapted for the reception of a plug on a cable, so marked onthe machine. Adjacent to the cable receptacle and connected to it 's. receptacle for a plug of a pad applicator and also a receptacle for a plug of a "plate applicator. The latter two are connected in series with one another through small impedance coil 3l which enables the condenser 21 to be used for the tuning of the plates to the circuit.

Briefly then, the short wave frequency is governed essentially by condenser I and tank coil .3, while ultra shortwave frequency is governed by condenser I and coils 8 and 9. noted that while condenser I in and of itself is of high capacitance, still in the latter instance of ultra short wave generation its effect taken in conjunction with the capacity of the tubes is low. These elements are common to the plate circuit whether it be operated at short wave or ultra short wave frequencies, but, in the one instance the grid circuit selectively effects resonance of the high inductance, high capacitance circuit path, while in the other instance the grid circuit selectively efiects resonance of the plate circuit path of low inductance and low (distributed) capacity.

The lead 32 at the other side of the output circuit contains "cable," "pad" and plate receptacles arranged similarly to those previously described.

As previously explained, a feature of th invention contemplates the control of the. circuit with the generation of short wave or ultra short wave occurring in accordance with the type of applicator the doctor has selected and. connects to the machine. For this purpose a switch indi-,

cated generally at 33 is employed; this switch in the preferred structure is located adjacent acable plug receptacle so that it is physically operated when one of the cable plugs is inserted in one of the cable receptacles. The switch 33 normally is open and comprises a movable contact 34 and a stationary contact 35. As the plug is inserted in the receptacle it engages the movable contact and thereby actuates the switch.

Thus, as shown in Figure 2, the plug or connector through which an electrode is connected to the oscillator circuit is illustrated at 45. The end of this plug is positioned to engage a high frequency insulator boss 46 which extends from theswitch 33 with the respective terminals of a coil 33 of a high frequency relay designated generally at 39. The high frequency relay circuit is energized from an appropriate power source as illustrated in the drawing.

This relay is of the conventional high frequency type and includes a core 40 and an armature illustrated diagrammatically at 4|. The armature carries a contact 42 which is movable into and out of engagement with the stationary contact 43. The armature is actuated by a spring so that contacts 42 and 43 normally are held into engagement with one another. The relay is arranged so that when it is energized the magnetic field produced by thecore of it is capable of operating the armature 4| to separate the contacts 42 and 43. Contacts 42 and 43 are connected in a shunt lead 44 which extends across grid coil 16. Therefore, when the contacts 42 and 43 are in engagement this grid coil is shunted. In. the normal operation of the circuit just described switch 34 is open and the grid coil I6 i short It should be an ultra-short wave machine.

circuited. The ultra short wave coils l4 and IS in the grid circuit furnish the excitation to the vacuum tubes I and 2- and in the plate circuit the ultra short wave tank coils 8 and 9 are excited to determine the oscillation of thegenerator as previously, described are of low impedance and the plate circuit is of low capacitance also. In this circuit path the total capacity is the distributed capacity through the tubes and the remainder of this circuit path. Under these conditions the condenser 'l operates as an effective short circuiting device relative to the short wave tank coil 3, and therefore this coil does not substantially influence the wave length of the oscillations.

When a plug of a drum applicator is inserte into the receptacle marked drum adjacent the switch 33 the plug of the applicator automatically effects the closure of the switch by bringing contact 34 into engagement with contact 35. This operation closes the high frequency relay circuit. The relay in turn is energized and the magnetic field is set up whereby the contact 42 i moved out of engagement with contact 43, thereby installing the grid coil It in the grid circuit.

The grid circuit now is comprised of the total impedance provided through the ultra short wave grid coils l4 and I5 and the grid coils l6, and the excitation furnished to the electron tubes is of such an order that short wave tank coil 6 in the plate circuit is energized. The inductance of a short wave tank coil and the capacity of condenser I are relatively high. Therefore, the circuit operates as a short wave generator, the wave length being determined essentially by the tank coil 6 and the condenser 1 in the plate circuit. The excitation in the grid circuit is derived principally through the grid gized, whereby the armature is permitted to move under the influence of its actuating spring to bring contacts 42 and 43 back into engagement and the machine therefore is restored to operation as an ultra short wave device.

As an alternative procedure, those skilled in the art readily will understand that a machine These coils as v constructed in accordance with the invention readily may be arranged to operate normally as a short wave generator, circuit switching means being provided for conversion of .it into an ultra short wave generator in a manner substantially opposite to the procedure just described.

I do not desire that the improvement be limited to the particular detailed embodiment herein disclosed but only by the scope of the claims which follow.

Having described my invention I claim:

1. A diathermy machine comprising an electron tube oscillator having a plate circuit including a high inductance, a low inductance connected in series with the high inductance and a high capacitance shunting the high inductance, a grid circuit having high inductance and also havinglow inductance connected in series therewith, the said inductances in the grid circuit and the inductances, high capacity and distributed capacity of the plate circuit all being so proportioned that the oscillator is capable of being resonated as a short wave generator and also being so proportioned that, when the high inductance in the grid circuit is short circuited,

the oscillator operates as an ultra short wave generator, a first set of receptacles for the reception of diathermy electrodes best suited to be operated on short wave energy, a second set of receptacles for the reception of diathermy electrodes best suited to be operated upon ultra short wave energy, and means for short circuiting the high inductance of the grid coil to cause the oscillator to operate as an ultra short wave generator, including a switch positioned adjacent a receptacle of the second set, whereby the insertion of an electrode in said receptacle physically operates said switch to cause short circuiting of said grid coil of high inductance in the grid circuit and thereby causes said oscillator to furnish ultra short wave energy on which the electrode inserted into said receptacleis best suited to be operated.

2. A diathermy machine comprising an elec= tron tube oscillator having a plate circuit and a grid circuit, the plate circuit including a high inductance, a low inductance connected in series with the high inductance and a high capacitance shunting the high inductance, a grid circuit including a high inductance andlow inductance connected in series therewith, the said high inductance of the grid circuit and the high inductance and high capacitance of the plate circuit being so proportioned as to enable the oscillator to resonate at a given frequency in the short wave range, and the low inductance of the grid circuit being so proportioned to the distributed capacity of the plate circuit as to enable the oscillator to operate at a given frequency in the ultra short wave range when the high inductance of the grid circuit is short circuited, means for selectively short circuiting the high inductance of the grid circuit, the said oscillator normally operating at one of the given frequencies and operating at the other of the frequencies when the short circuiting means is operated, a patient circuit coupled with said oscillator and including a first set of receptacles for the reception of diathermy electrodes best suited to be operated at a given one of said frequencies and including a second set of receptacles for the reception of diathermy electrodes best suited to be operated at the other of the given frequencies, and a switch for controlling the means for short circuiting the high inductance of the grid circuit, said switch being located adjacent a receptacle of a given one of said sets of receptacles, so as to be physically operated when a given electrode is connected thereto, whereby the oscillator is caused to resonate at the given one of said frequencies at which the electrode connected to 

